File.



J. H. BARKBR.

Patented Aug. 11, 1914.

FIG. l

FIG. 2

JOHN HENRY BARKER, 0F` SIIEFFIELD, ENGLAND.

\ FILE.

Specification of Letters Patent.

Patented Aue. iill, 1914.

Application filed May 12, 1914. Serial No. 838,181.

T0 all whom it may concern.'

Be it known that I, Jol-IN HENRY BAKKER, M. I. Mech. E., a subject ofthe King of England, and a resident of Sheffield, in Yorkshire, England,have invented certain new and useful Improvements in or Relating toFiles, of which the following is a specification.

This invention relates to files of the kind which are provided withclearance grooves of greater depth and pitch than the file-cuts .for theescape of the filings, its object being to provide an improvedarrangement of the clearance grooves in order to produce a moreeflicient tool. According to the present lnvention, three differentseries of 'clearance grooves are provided, and of these, one series isarranged approximately at right angles to the axis of the file while theother two series are inclined thereto and to each other. Preferably theinclination of the last two series is equal and the three series are sodisposed as to divide the file surface into a number of equal triangularareas.

In the accompanying drawings Figure l is a plan of part of a single-cutfile accord ing to this invention. Fig. 2 is an elevation of Fig. l.

Like letters indicate like parts throughout the drawings.

In carrying out this invention three series of clearance grooves A, Band C are formed in the face of the file. Of these, the series A isarranged approximately at right angles to the file axis, as shown inFig. l, while the two series B and C are both inclined thereto and toeach other. rlhe preferred disposition of the three series of clearancegrooves is shown in Fig. 1, the inclination of B and C to the axis beingequal and all three joining the edge of the file at approximately thesame place, thus dividing the lile surface into a number `of equaltriangular areas. As illustrated, the series C is parallel to the filecuts D althoughfthe inclined clearance grooves may be formed` at adifferent angle with the le axis from the file cuts if desired. Theclearance grooves may intersect one another or not as desired; in thedrawings only the series B and C intersect one another.

The present invention is primarily de- Copies of this patent may beobtainedfor've cents each, by addressing the Commissioner of Patents,

Washington, D. C.

signed for a single-cut file, but may plied to a double-cut file.

The clearance grooves A, B and C may be provided by any desired method.For example they may be made in an ordinary lile cutting machine byincreasing the power or the number of blows of the chisel, or they maybe cut by a milling tool either before or after the file-cuts D aremade. In another method the deeper cuts or grooves are formed during therolling of the file blank.

What I claim and desire to secure by Letters Patent is:-

l.' In a file provided with clearance grooves,the provision of threeseries of such grooves of which one series is arranged approximately atright angles to the file axis, while the other two series are inclinedthereto and to each other substantially as set forth.

2. In a file provided with clearance grooves, the provision of threeseries of such grooves of which one series is arranged approximately atright angles to the file axis, another series is parallel with the[ile-cuts and the third series is at right angles to the file-cuts,substantially as set forth.

3. In a file provided with clearance grooves the provision of threeseries of such grooves of which one series is arranged approximately atright angles to the file axis, while the other two series are sodisposed in relation thereto and to each other as to divide the filesurface vinto a number of triangular areas of approximately equal size,substantially as set forth.

d. In a file provided with clearance grooves, the provision of threeseries of such grooves of which one series is transverse, being'arranged approximately at right angles to the file axis, while the othertwo series form diagonale between the members of the transverse series,substantially as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JOI-IN HENRY BARKER.

be ap- `Witnesses ARTHUR I-I. GREENWOOD, Lori-IER J. IARR.

